This invention relates to a device which forms a protected passage for communication cables, pipes or hoses in the well fluid inflow portion of production tubing in wells of the kind used in the recovery of petroleum.
In recent years, in particular when horizontal wells are used, it has become usual to use the so-called “open hole” technique. The technique involves that in a portion of the well, typically in one or more of the petroleum-producing zones of the reservoir, no casing is set. Thus, when the production tubing is to be run, it must be moved into and through an open well bore, within which it lies slidingly against the well formation. To prevent sand from the formation from entering together with the inflowing well fluid, and to support the formation wall and thus prevent the well bore from collapsing, it is common to set so-called strainer pipes in the petroleum-producing zones of the reservoir. In their outer jacket, the strainer pipes are provided with through openings in the form of fine bores or slots designed to admit well fluid but prevent formation sand from reaching the production tubing located within.
The development of the production technique in question has resulted in the discovery of an increasing requirement for using downhole sensors and actuators. Sensors are used, for example, for measuring one or more of the physical properties of the well fluid, whereas actuators may be used, for example, for choking well fluid from one or more of the zones of the reservoir. Communication between such downhole equipment and the surface is normally accomplished by means of electrical cables, whereas energy is supplied by means of electrical wires and/or hydraulic pipe or hose connections.
According to known technique, cables and pipes or hoses of the kind in question are placed in protective channels arranged for the purpose externally on the strainer pipe. It is obvious that when production tubing is being run, as the strainer pipes are subjected to displacement and rotation against the uncased formation, such protective channels are subjected to huge mechanical loads. Experience goes to show that during the running operation damage will occur, to a considerable extent, on these protective channels and the cables, pipes or hoses carried inside the channels.